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DBU (1.18g, 1.18 mL) was added dropwise to compound 16 (2.00 g) and N-N’-bis-Bocguanidine (2.69 g) in a solution of DMF (100 ml) was cooled to -10 C. After 2.75 hours, the solution warmed to O degrees C, and then was poured on to 500 mL of water and 300mL of ethyl acetate. The aqueous layer was extracted with an additional 100 ml of ethyl acetate and then quenched with 50 ml of brine . The aqueous layer was then extracted with ethyl acetate twice each with 100 milliliters of ethyl acetate, and then washed with water (three times with each wash of 200 ml) and brine(200 ml). Magnesium sulfate was used as a dehydrating agent, and the remaining solvent was then removed under reduced pressure. The organic brown residue was purified using flash chromatography on silica with an eluent solution of 10% ethyl acetate in hexanes and then 20% of ethyl acetate in hexanes.
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DMF,dimethyl-formamide |
N-N'-bis-Bocguanidine |
DBU, 1,8-Diazabicyclo[5.4.0]undec-7-ene |
Flash Chromatography: Means of separating a mixture of compounds based on their relative polarities by pushing them through a column of silica gel with pressure from nitrogen gas. |
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